NAJAF, Iraq, Oct. 16 -- No one in Najaf wore a bigger smile to the polls Saturday than Falah Hassan Sarraf.

The electrical engineer and his wife were so keen to vote in Iraq's constitutional referendum that they hardly slept the night before, he said. And they brought along their three young daughters to share in the moment.

But when asked what they liked so much about the document, which even the Shiite Muslim politicians who dominated its drafting have acknowledged is far from perfect, Sarraf gave what turned out to be a common response in this Shiite spiritual center.

"We are with the marjiya ," he said, referring to the members of the highly influential Shiite religious council that asked followers to support the referendum. "If they say 'Vote yes,' we vote yes."

Millions of Iraqis voted similarly Saturday on a referendum issue that appears to have passed despite intense opposition from Sunni Muslims, although final results have not been released. Even as the former dictatorship moved to the brink of formalizing its rebirth as a nation of laws, voters across southern Iraq, home to some of the world's most sacred Shiite cities and shrines, left little doubt that their loyalties lay with the country's clerics and not its politicians. On polling day in Najaf, where local officials say more than 80 percent of voters backed the constitution, a majority of those interviewed said they had never read a word of it or knew little or nothing about its contents.

"There are two types of authority: political and religious. And of the two, religious is higher," said Mohammad Khuzai, a representative of Bashir Najafi, one of Iraq's four top Shiite clerics, whose rulings on religious, cultural and occasionally political matters can carry more force than law.

But turnout in Najaf and across Shiite-majority southern Iraq was far lower than expected Saturday. An estimated 50 percent of the roughly 450,000 eligible voters in Najaf province went to the polls, compared with more than 80 percent in January's landmark legislative elections. That raised the prospect that the dictates of Shiite clerics had lost some weight since January, when they declared voting an Islamic duty and endorsed Shiite religious parties such as Dawa and the Supreme Council for the Islamic Revolution in Iraq.

Those parties earned overwhelming support from voters, but the government they formed in late April has disappointed many Iraqis by failing to improve the country's infrastructure and security in nearly six months in office.

"The marjiya tell us, 'Say yes,' but I don't see any purpose," said Abbas Father, an unemployed resident of Karbala, a city west of Najaf that is home to the shrine of Imam Hussein, whose death in battle there in the 7th century was a pivotal event in the history of Shiite Islam.

"They told us last time to support the alliance and I did," Father added, referring to the clerics' tacit endorsement of the Shiite coalition that won a majority in parliament. "What did we get?"

Under Saddam Hussein, Shiites were relegated to second-class status. Their clerics largely eschewed politics -- partly in keeping with the dominant "quietist" strain of Shiite thought and partly to survive.

They emerged into public life after the U.S.-led invasion with new freedoms and an undiminished following. To the surprise of U.S. officials here, Grand Ayatollah Ali Sistani, the marjiya's most influential member, soon called for democratic elections.